Tuning means



Jan- 10, 1950 B. A. scHwARz :TAL 2,494,007

TUNING MEANS Fled April 3. 194'? 2 Sheets-Sheet l Jall- 10, 1950 a. A.scHwARz ET Al. 2,494,007

TUNING mms Filed April 3, 1947 2 Sheets-Sheet 2 VMM Patented Jan. I,1950 2,494,001 TUNING MEANS Bertram A. Schwarz, Kokomo,

J. Fichter, Rockford, Ill.. Motors Corporation, Detroit, Mich.,

tion of Delaware nun-ma Lum; assigner: to General a corpora- AppllcationApril 3, 1947, Serial No. 730,244

4 Claims. (Cl. Il-10.33)

'This invention relates to means for accurately positioning adjustableapparatus used for tuning radio receivers. In altering the tuning ofradio receiving equipment so that various frequencies are utilized andthe set changed to receive difierent stations, the resonant frequency ofthe receiver can be changed in the several stages necessary by eithervarying the inductance or capacity in that circuit. Both means arecommon and while the mechanism disclosed in the present application isshown associated with a variable condenser, it could as well be utilizedfor changing the position of means for varying inductance. Originally,most radio receivers were tuned by the manual manipulation of a knob anddial to which the capacity or inductance of the desired radio circuitswere directly mechanically connected for tuning over the band to receivediierent stations.

Later the sets were provided with so-called push button" tuning whereinreciprocating or pivoted buttons associated with levers were provided sothat the operator by merely applying pressure to said button wouldimmediately bring the receiver to a pre-set station. A number ci thesebuttons were provided so that a number of favorite stations could be setup initially and upon the application of force to any one of saidbuttons a desired station would be brought in. Particularly inautomotive receivers. however, where the locale of operation is changedfrequently. it was necessary to reset the adjustable means on thevarious plungers to new positions for the new stations and on some ofthe earlier models it was necessary to remove a portion oi' the casingto change the cam position inside the receiver with a screw driver orsimilar apparatus. Later, means were provided for unlocking the cams orother adjustable indexing equipment irom the outside, but in themajority of these it was still necessary to utilize both hands, one tohold the plunger in and the otherto adjust and tighten the equipment forlocking the cam in position.

It is therefore an object of our invention to provide pre-set indexingmeans which can be unlocked by the application oi' force additional tothat ordinarily used for tuning and without the necessity ofmanipulating other devices` It is a further object of our invention toprovide indexing means which can be unlocked by additional travel of theplunger in the direction of movement at which time the receiver can bemanually tuned to some new station and the mere removal of theadditional pressure on the push button immediately locks the device inas its new position, and thereafter it will return 2 the tuningmechanism to the new station.

It is a still further object of our invention to provide pre-set pushbutton tuning means which is spring locked and capable of unlocking onthe application of force to overcome said spring pressure forre-setting.

With these and other objects in view which will become apparent as thespecincation proceeds, our invention will be best understood byreference to the following specincation and claims and the illustrationsin the accompanying drawings, in which: 1

Figure l is a top plan view showing a tuning mechanism of our design asapplied to a variable gang condenser for tuning purposes;

Figure 2 is a sectional view taken on line 2 2 of Fig. i;

Figure 3 is a sectional view taken on line I I of Fig. 2;

Figure 4 is a sectional view similar to Fig. 2 showing the parts of theapparatus in their intune or setting position;

Figure 5 is an enlarged sectional view taken on line 5 5 of Fig. 4:

Figure 6 is an enlarged sectional view taken on line 8 6 of Fig. 4;

Figure 7 is a side elevation of single tuning plunger showing a modiedform of our invention;

Figure 8 is a sectional view taken on line 8 8 of Fig. 7;

Figure 9 is a side elevation of a further modiiled plunger design:

Figure l0 is a sectional View taken on line III I I of Fig. 9; and

Figure 11 is a sectional view taken on line Il ll of Fig. 6.

Referring now more particularly to that species shown in Figures 1 6,there is disclosed in Fig. 1 a variable condenser 2 consisting of a.series of stator plates 4 between which lie a series o! adjustable rotorplates 6 for changing the capacity in the several stages of amulti stageradio receiver for tuning purposes. The rotor shaft is provided at oneend with means for manually setting the same to diierent positions whichin this instance is shown in an exemplary form as a knob or dial 8. Theframe of the condenser is provided with two upstanding portions l0 andi2 which extend for the full longitudinal length oi' the same and have aseries of slots therein in which a series of plunger means for so-calledpush button tuning are mounted for reciprocation.

These plungers are all identical and one therefore will be described indetail. The reciprocating plungers orlevers are o! irregular shapemchasshownat Ilandaremadeofapieceot nat material bent into the desiredconiiguration andextendingilrstthroughanopening Il inthe front wall Ilof the condenser trame and then.beingreducedinverticalsectiontoasmallrear portionIlwhichextendsthroughanaligned opening Il in the vertical plate il o!the condenser housing or trame. Thus the member il may movelongitudinally toward and away from the condenser per se. This member Ilis provided with an upstanding arm Il integral therewith which in itsouter-most position is adapted to press against the inner surface of theiront partition i! and act as a limit for movement in that direction. Atension spring Il connected to the frame or partition Il and to anopening in each member il is provided to bias the plunger normally tothe position .lust identiiied.

The upstanding arm Il is provided on its inner side with an arcuatesurface Il whose radius is determined by the curvature .of the means formoving the rotor which is directly seated thereon. Referring morespeciiiealiy to Fig. 2, the rotor plates 2l are shown as pivoted aroundaxis Il which is the shaft to the end of which knob l is applied.Parallel with the shaft and spaced on each side thereof, there areprovided two insulated bars Il, which extend substantially the fulllength oi the tuner and are connected together at various spaced pointsalong the shaft by supporting members Il, this whole assembly beingrigidly connected to the rotor plates to turn therewith. The bars 32 areadapted to be contacted by the arcuate or half-moon cams 8l, which areadapated to ride in the arcuate seats It of the plungers. and havesubstantially the same curvature. Each arcuate cam is provided with twoprojecting points Il, which are adapated to engage either of the barsII. depending upon which way the rotor is to be turned and tc move it toits new location. Therefore, the arcuate surface 26 is determined by theradius from the center o! the shalt Il to this surface when theprojecting points Il engage the bars l! lor i'ull in-tune position.

The means for maintaining the arcuate cam tl in a predetermined setposition on the arcuate surface It is a saddle Il pivoted at 42 to thetop of the proiecting arm I! and extending down on both sides of themember Il and being crossconnected at I4 to extend over around thecenter of the arcuate cam 3l so that when the lower part of the saddleIl is pulled back around its pivot 42 this section Il will tend to torcethe arcuate cam Il iirmiy against the surface 2| and frictionally lockthe same. The portion of the saddle 4l which extends down on each sideof the member Il is provided at its lower extremity with a slottedsection Il and the slide I4 at that point is provided with an apertureIl in which a longitudinally adjustable block Il is positioned. Thisblock It is adapated to engage the sides of the apertures in the saddleand to move the saddle about its pivot as the block moves longitudinallyof the plunger.

To move this block there is provided a short shalt l! whichis threadedinto the block 50 and this rod or shaft runs longitudinally of theplunger and extends through and is trunnioned in an upstanding ear Il.The outer end of the shaft I2 is provided with a series oi coarse spiralthreads It which engage with the inner threaded surface Il of a collarIt which collar is supported within a longitudinally movable position,the saddle Il locks the adjustable cam 3l in a definite set position onthe arcuate seat Il. When the operator desires to rotate the variablecondenser to tune in a station representative of the present position ofthe adjustable cam 2t. pressure is applied to the push button Il alongits longitudinal axis. The plunger Ii then slides in axially to bringthe cam li toward the axis of the shaft SII and one oi the ends Ilengages one of the cross members I2. When this occurs therotary assemblybegins to rotate around the axis of the shalt 3l, and such actioncontinues until the other extreme end Il of the cam Il engages theopposite cross member 32. This brings the rotary condenser to a definiteset position and the inward motion oi the plunger stops. Upon release oithe manual pressure, tho spring 2l immediately returns the plunger toits outermost position.

If now, however, it is desired to set this particular plunger to somenew station, manual pressure is applied to the push button tl, as inprevious instances. and the set is tuned to that particular position.Pressure is now increased on the end of push button t8, which actionforces the block l2 inwardly, compressing spring Til. Since the interiorsurface or this block is provided with threads which cooperate with thespiral threads Il on the shaft 52. the inward movement of the block I2through these cooperating threads will cause rotation of the shaft I2,which in turn will cause a change in the relative position of said shaft52, and said block 5I, as the two are in theraded relation.4 Thismovement of the block il along the threads oi the shaft i! will besufncient to unlock the saddle Il and permit the arcuate cam Il to slideon its seat 2B. Now by the application of rotary force to the knob 8,the set may be tuned to its new station while holding the push button 88in this position. The movement of the cross members $2 will now causethe cam It to move on its seat and assume a new position. When the newstation has been tuned in the push button It may be released, the spring1li will now force the block B2 back into its outward position, causingcounter-rotation oi the shaft 52 and locking action of the block 50 toagain move the saddle l0 about its pivot and lock the cam 3B in its newposition.

Such action, of course, can be duplicated for the other push buttons ifit is desired to reset any of them. It is thus seen that normallylongitudinal motion of any push button will merely tune the set to somepre-set station, but that if it is desired to change the setting of thestation of any push button, additional pressure on the same push buttonwill unlock the settabie cam and the receiver may now be tuned to itsnew station, and upon release oi this same button, the cam will now belocked to thereafter tune the set to the new station. Accidentaladditional pressure on one o! the buttons will not detune the receiverbut will only unlock the cam in its original set position which willimmediately become locked upon a removal of pressure. To change thesetting the manual knob must be rotated. The above construction is, ofcourse, only one of many ways in which additional pressure on alongitudinal movable plunger may unlock a pre-settable device forresetting to a new position.

Figures 'l and 8 show a modified form oi' accomplishing that same resultand in that instance only one of the like plungers is shown which wouldbe similar to plungers Il shown in the preceding gures, and wouldcooperate with the same type of variable condenser as shown therein. Inthat instance, the plunger i4' as betere, has a vertical extension 22',at the top of which there is pivoted a similar saddle lli'. The saddleas before, extends downwardly on each side of the vertical extension 21'and has cross straps M' which tend to hold the arcuate cam It' on itsseat 26'. In this instance, however, the plunger il is provided with anopening 8D in which there is mounted a compression spring Il, one end ofwhich engages a washer Il mounted in the end of the slot 80, and theopposite end of which engages both sides of the saddle Il. This thentends to force the saddle in a clockwise direction about its pivot,as'shown in Figure 7, and therefore tends to maintain the cam Il' lockedagainst its arcuate seat 26'.

The plunger il is also provided with a suidable member 85,' which slidesin a slot 81, and has extending ears projecting on both sides of theslot. This member is then bent backward parallel to the plunger and thenagain in the nature of a U-shape, the two portions extending verticallyto the plunger, being provided with openings B6 and Il, through which' asmall rod lo projects, which rod carries on its outer end a push button82. A set screw 94 is provided to hold the U-shaped member on rod 9B ina given position. The end of the plunger Il' is provided with a plate U9through which the rod 90 projects and between this plate 89 and thedownwardly extending leg of the member B5 there is a second compressionspring 9i. This rod 90 ex tends through openings Il and I8 and carriesin threaded relation on its inner end a diagonal plate 95 one end ofwhich presses against the low extremity of the saddle 40', and the upperend of which presses against the surface of the slideable member 85.

In this form, therefore, as the push button is forced in the plungerwill immediately move to carry the cam 36' against the horizontalmembers I2 of the condenser, until both projections 3l' engage thehorizontal parts. This tunes the set as before. If we now wish to reset,additional pressure causes the member I5 to be moved with relation tothe plunger Il', which additional inward travel is imported throughplate 86 with the resultant leverage to the lower end of the saddle lliwhich then tends to move the saddle in a counter-clockwise or unlockingdirection. When suiilcient pressure is applied, the force oi' spring l2is overcome and the cam 36' is unlocked for movement to anotherposition. Upon tuning the set to such position and removal of the pushbutton pressure. the device is now locked in the new position to tune insome other station.

A second modified form of plunger and locking means is shown in Figures9 and l0. in which the plunger Il" is as before provided with anupstanding arm 22". but in this instance there is applied on each side ashort strip H2, which carries pivots il tor the saddle lol. Each of thesaddle arms on opposite sides are connected by a cross strip Ill, whichmaintains the cam It" on its arcuate seat 28". The ends ot the saddlewhich extend down over the plunger are again provided with openings IMwithin which an adjustable block IDI is mounted, which block can bemoved longitudinally ci the plunger by a rod ill, which is connected toa push button (not shown). A relatively strong coil compression springilil is tted in an aperture in the plunger and engages the lower end oi'the saddle to tend to move it in a clockwise or locking direction aroundits pivot. In this case as in previous cases, initial movement of theplunger actuated by a push button causes engagement of the cam li" withthe horizontal bars 32 oi' the condenser for tuning. Additionalpressure, however, overcomes the force of the spring illi to release thearcuate cam Il" for resetting purposes.

We claim:

1. In tuning means for a radio receiver, rotatable means for tuning saidreceiver to diilerent stations, reciprocable means mounted for movementtoward said rotatable means. an adjustable cam on said reciprocablemeans, pivotal frictional locking means for said cam, spring biasingmeans to maintain said looking means in locked position, shaft meansrotatably mounted on the side of the reciprocable means and threadedlyengaging said locking means at the inner end to move the locking meansupon shaft rotation, said outer end being provided with coarse spiralthreads and manually engageabie means slideably mounted on saidreciprocating means and having an internal threaded surface surroundingthe spiral threads so that upon relative movement of the two the shaftwill turn and unlock the locking means.

2. In a slideable assembly carrying an adjustably positionable actuatingcam, locking means for the cam mounted cn said assembly, rotatableactuating means for the locking means rotatably mounted on said assemblyand manually engageable slideable means mounted on said assembly andmoveable relative thereto interconnected in driving relation with therotatable actuating means to cause rotation of the latter upon relativereciprocation of the former to lock and unlock said cam.

3. In a slideable assembly carrying anadjustably positionable actuatingcam, locking means for the cam mounted on said assembly, rotatableactuating means for the locking means rotatably mounted on saidassembly, manually engageable slideable means mounted on said assemblyand moveable relative thereto interconnected in driving relation withthe rotatable actuating means to cause rotation of the latter uponrelative reciprocation of the former to lock and unlock said cam, andspring biasing means between the manually engageable means and theassembly to tend to cause the whole to move together but which uponapplication of additional pressure permits relative motion between theparts and causes the looking means to be actuated.

4. In tuning means for a radio receiver, rotatable means for tuning saidreceiver to different stations, an assembly mounted for reciprocatorymotion toward said rotatable means, said assembly consisting of a bar, acam adjustably mounted on said bar and adapted to engage the rotatablemeans upon travel toward the same, locking means for the cam, meansrotatably mounted on said bar connected to the locking means to actuatethe same upon rotation,

manually engageable means mounted on said bar for limited relativemovement therewith lnter- REFERENCES mm connected with said rotatablemeans on said bar The following references Aare of record in the torotate the same when relative motion occirs file of this patent:

between the manually ensageable means and he 5 bar no lock or unlock thecam and spring biasing Y UNITED STATES PATENTS means to restrainrelative motion between the Number Name Date manually engageable meansand the bar so that 2,266,711 Crosby et al. Dec. 16, 1941 under normalpressure they will move as a unit. 2,285,102 Tea! June 2, 1942 BERTRAMA. SCHWARZ. 10 LUDWIG J. FIGHTER.

